"After drawing blood that day, his mind seemed to have become preoccupied and his hands would shake during dinner," she said.
She also said her husband would disappear for days at a time, but always returned with money which she assumed was from casual work.
While it may seem strange not to notice certain things about your partner, Zhang is not alone.
She, along with several other women, appeared to have no idea who they were really married to.
JULIE BAUMEISTER: SUSPICIOUS WIFE
When her 13-year-old son found a skull while playing on the family property, Julie Baumeister sensed something wasn't right.
She asked Herb, her husband of 23 years, if he knew anything about it but he told her the bones belonged to a medical school skeleton owned by his late father.
The Indianapolis woman later forgot about it until police searched their property and discovered human remains.
It emerged while she and the children went away for part of the summer her husband was cruising gay bars looking for victims.
The killings took her by surprise and she remembers having to be told what homosexual homicide was, according to People.
She revealed how her husband acted like the perfect family man who was very hands on with his children.
Rader, whose cries struck fear in the US Wichita district, in Kansas, murdered 10 people between 1974 and 1991.
In June 2005, Rader pleaded guilty and coldly explained in court how he selected, stalked and strangled his 10 victims between 1974 and 1991.
Rader, who worked as a city by-laws supervisor - a job which gave him access to other people's yards and homes, was planning his 11th kill when he was arrested in 2005.
The sadistic killer is currently serving a life sentence for each of his victims.
Rader's daughter, Kerri Rawson, said her father is a psychopath with an ego.
"You can't take anything he says as truth," she said upon the release of a new book, Confession of a Serial Killer: The Untold Story of Dennis Rader, the BTK Killer.
Fayian was married to Russian cannibal serial killer Andrei Chikatilo, regarded as one of the worst serial killers the world has ever seen.
Russian serial killer Andrei Chikatilo who confessed to murders of 56 boys, girls and women after being tracked down by psychiatrist Alexander Bukhanovsky in 1990. Photo / News Corp Australia
Andrei Chikatilo killed, raped, murdered and ate as many as 100 people, including many young children yet his wife seemingly had no idea.
Married for 30 years, she told police she believed her husband may have been capable of an affair but was gobsmacked at the evidence they presented her with to show his crime was far worse.
She told police they didn't have sex as he told her he was incapable of it.
She also told him he had spent nights away from home, had scrubbed his bloodstained clothes and was even suspended from his teaching job amid molestation rumours.
Fayian appeared to support her husband right up to the end, even providing him with an alibi over the death of a nine-year-old girl, something he later confessed to.
Authorities were only able to find evidence to link him to 53 murders and the Butcher of Rostov was sentenced to death in 1992 before being executed two years later.
JUDITH RIDGWAY: FAITHFUL BELIEVER
When Police told Judith Ridgway, nee Mawson, that her husband Gary was the notorious Green River killer, she initially refused to believe it.
Gary Ridgway pleaded guilty to 48 murders. Photo / News Corp Australia
In 2001, her husband of 13 years had been arrested and charged with the murders of dozens of women.
"No I don't believe that," she told a detective at the time. "He's always been so, so gentle and caring."
She was even prepared to stand up in court and reveal everything that's good about him, SeattlePI reported.
But the killer's third wife never got that chance after he pleaded guilty to 48 murders as part of a plea deal to save him from execution.
Police believe he killed more than 70 people, all of them prostitutes and/or runaways in the Seattle and Tacoma, Washington areas during the 1980s and 1990s.
Mawson, who met her husband in 1985 said she fell completely in love with him, and revealed how he treated her like a perfect lady.
She admitted there were some clues and indications of his crime spree, including periods away from home, but dismissed them at the time.
But over time she learned and accepted the truth about her husband's crimes, changing her surname to back to Mawson.
She later revealed how she would never forgive her husband for what he did.
Mawson wrote a book called Green River Serial Killer: Biography of an Unsuspecting Wife in 2007 which went on to become a bestseller.
